Wits end on chain tension

Hello everyone,

I have a single speed bike and I am at my wits end on this chain tension screw on the back wheel. Every time I remove the wheel it's such a pain to correctly dial in the chain tension - I have tried pliers, my hands - using these screws on both the size of the wheel, I end up incorrectly replacing the chain and wheel and so the bike wobbles when I ride.

How do I correctly keep the tension on both the size of the wheel since I have to manually tighten the screw on both the size. I saw there was something called a chain tensioner.

Any help is really appreciated